The present invention relates to imaging systems, and more particularly, to a method for improving the resolution of images.
The present invention may be more easily understood with reference to imaging systems that utilize lens systems with very wide angles which are particularly useful in teleconferencing systems and the like. Such images capture essentially all of a scene in front of the camera without requiring that the camera be moved.
While such lenses are very useful, the resolution of the image produced thereby is often lacking in the regions of the image that originate at angles that are far from the center ray of the camera lens. A typical camera utilizing a fisheye lens consists of the lens with an image sensor such as a CCD array in the focal plane of the lens. The CCD array typically has a uniformly spaced array of pixels. Since the lens maps much larger solid angles to the pixels that are far from the center ray of the lens, these off-axis pixels have much poorer resolution than pixels near the optical axis. Hence, while the fisheye lens provides a large viewing solid angle, the usefulness of the image at the off-axis points is limited.
In principle, the image can be improved by combining a number of images to form a single image having improved resolution. This type of super-resolution system has been used with conventional lenses for some time. In the typical prior art super-resolution system, a series of images are taken at different camera positions. This is accomplished by moving the camera so that each image represents the image taken by a camera that is displaced relative to the previous location. If the direction of the optical axis is defined to the z-axis, the camera is moved in the x and y directions. A number of such displaced images are then combined to form a single image having a resolution that is higher than any of the single images taken.
Unfortunately, this type of prior art super-resolution system is poorly suited to fisheye lenses. Since pixels represent the light collected from directions of space that subtend different solid angles, the complexity inherent in setting up and solving the super-resolution problem makes the application of the prior art methods very expensive as measured in computational time or storage requirements.
Broadly, it is the object of the present invention to provide an improved super-resolution system for use with lenses such as fisheye lenses.
These and other objects of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and the accompanying drawings.
The present invention is an image recording apparatus and method for using the same to generate a high-resolution image of a scene from a plurality of low-resolution images taken by the apparatus. The apparatus includes an array of image sensors and a lens for imaging the scene onto the array of image sensors such that each image sensor receives light from a different portion of the scene. The apparatus also includes an actuator for rotating the image array about the optical axis. A controller reads-out the image array at each of a plurality of angles of rotation with respect to the optical axis to provide a plurality of low-resolution images that are combined to form the high-resolution image.